With increasing power of personal computers, a diversity of office machines can be employed with the personal computers to achieve various purposes. The diverse office machines, however, occupy lots of space. A multifunction peripheral having multiple functions in one structural unit, for example the functions of a printer, a scanner, a fax machine and/or a copy machine, is thus developed. As a consequence, the processing capability of the multifunction peripheral is increased and the operative space thereof is reduced.
Nowadays, the printer, a scanner, a fax machine, a copy machine or the multifunction peripheral usually has an automatic document feeder for successively and continuously feeding many paper sheets. After a stack of papers to be scanned are placed on the sheet input tray of the automatic document feeder, the sheet-feeding mechanism of the automatic document feeder will successively transport the paper sheets into the inner portion of the office machine so as to implement associated operations such as scanning, faxing, scanning operations and the like.
Referring to FIG. 1, a schematic cross-sectional view of a conventional automatic document feeder for use with an office machine is illustrated. The automatic document feeder 10 of FIG. 1 principally includes a casing 11, a paper-feeding mechanism 12, a transfer module 13, an ejection module 14, a paper input tray 15 and a paper ejecting tray 16. After a stack of paper sheets 151 to be scanned are placed on the paper input tray 15, the paper-feeding mechanism 12 may successively pick the uppermost paper sheets one by one into the passageway within the automatic document feeder 10. In addition, the pick-up module 12 has a stopping plate 121, which is sustained against the front edges of the stack of paper sheets 151, for facilitating smoothly transporting the paper sheets 151 into the paper feeding port. The office machine further includes an image processing module 3 and a glass platform 4 under the automatic document feeder 10.
After a stack of paper sheets 151 to be scanned are placed on the paper input tray 15, the paper-feeding mechanism 12 may successively pick the uppermost paper sheets one by one into the passageway within the automatic document feeder 10. Next, the paper sheet 151 is transported through the transfer channel 133 by the paper guide members 131 and 132 of the transfer module 13. Once the paper sheet 151 is transported across the glass platform 4, a first side of the paper sheet 151 is scanned by the image processing module 3. The paper sheet 151 whose first side has been scanned is then ejected to the paper ejecting tray 16 by the ejection module 14. For a purpose of performing a duplex scanning operation, the transfer module 13 further includes an inverting member 134 adjacent to the ejection module 14. After the first side of the paper sheet 151 has been scanned and a majority of the paper sheet 151 is ejected to the paper ejecting tray 16, the paper sheet 151 is turned over by the inverting member 134 and then fed into the passageway. Next, the paper sheet 151 is transported through the transfer channel 133 by the paper guide members 131 and 132 of the transfer module 13. Once the paper sheet 151 is transported across the glass platform 4, a second side of the paper sheet 151 is scanned by the image processing module 3.
Referring to FIGS. 2(a) and 2(b), schematic cross-sectional views of the paper guide member 131 of the transfer module 13 are illustrated. The paper guide member 131 includes a pressing plate 1311, a plurality of springs 1312, a plurality of rollers 1313 and a roller axle 1314. The rollers 1313 are sheathed around and secured to the roller axle 1314. For each roller 1313, two springs 1312 are respectively arranged at bilateral sides thereof. A first end of the spring 1312 is sustained against the roller axle 1314. A second end of the spring 1312 is sustained against the pressing plate 1311. During the rollers 1313 are rotated to guide and transport the paper sheet 151, the roller axle 1314 is rotated with the rollers 1313 in the same direction. Since the diameter of the roller 1313 is greater than that of the roller axle 1314, the center of the roller axle 1314 will be shifted when the rollers 1313 are rotated. For example, when the rollers 1313 are rotated in the anti-clockwise direction, the center of the roller axle 1314 may be shifted from the position A as shown in FIG. 2(a) to the left position B as shown in FIG. 2(b). Since the spring 1312 is sustained against the roller axle 1314, the contact surface of the roller axle 1314 is arc-shaped. Due to the arc-shaped contact surface of the roller axle 1314, the spring 1312 is readily aslant if the force exerted thereon is not even. Under this circumstance, the forces exerted on bilateral sides of the roller 1313 are also uneven and thus the paper sheet 151 is usually aslant upon being guided by the paper guide member 131.
Especially when a duplex scanning operation or a double-side printing operation is performed, the paper sheet 151 is turned over by the inverting member 134 and then fed into the passageway. Next, the paper sheet 151 is transported through the transfer channel 133 by the transfer module 13. If no additional means is used to correct the aslant paper sheet 151, the image quality of the paper sheet after scanned by the reading line of the image processing module 3 is reduced.
In views of the above-described disadvantages resulted from the conventional mechanism, the applicant keeps on carving unflaggingly to develop a paper guide adjusting mechanism and an office machine using such a mechanism according to the present invention through wholehearted experience and research.